Skin tightening device



FIG. 1 is a top, front, right side perspective view of the skin tightening device;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a back elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a top plan view thereof.

The structure in broken lines forms no part of the claimed design. 

CLAIM The ornamental design for a skin tightening device, as shown and described. 